Non-integral chrome zooms cause layout issues

[mattgodbolt]

If one has a two column layout and then uses Chrome browser zoom, under some circumstances the rounding/extra pixel allocation process adds an extra pixel, meaning the rightmost column in a row word-wraps off underneath and essentially vanishes.

Debugging, this is because the width() or height() in _setAbsoluteSizes in RowOrColumn.js returns a non-integral value. Later on, this means additionalPixel is also non-integral, leading to an extra pixel being given out in if contentItem loops.

I tried to write a test to reproduce it, but under normal circumstances one can't create a non-integral-sized element. I have a patch coming for the fix though.